Images

Frost at the Viking Lander 2 Site

Photo from Viking Lander 2 shows late-winter frost on the ground
on Mars around the lander. The view is southeast over the top of
Lander 2, and shows patches of frost around dark rocks. The surface is
reddish-brown; the dark rocks vary in size from 10 centimeters (four
inches) to 76 centimeters (30 inches) in diameter. This picture was
obtained Sept. 25, 1977. The frost deposits were detected for the first
time 12 Martian days (sols) earlier in a black-and-white image. Color
differences between the white frost and the reddish soil confirm that
we are observing frost. The Lander Imaging Team is trying to determine
if frost deposits routinely form due to cold night temperatures, then
disappear during the warmer daytime. Preliminary analysis, however,
indicates the frost was on the ground for some time and is disappearing
over many days. That suggests to scientists that the frost is not frozen
carbon dioxide (dry ice) but is more likely a carbon dioxide clathrate (six
parts water to one part carbon dioxide). Detailed studies of the frost
formation and disappearance, in conjunction with temperature
measurements from the lander?s meteorology experiment, should be
able to confirm or deny that hypothesis, scientists say.